Photosensitive diode structure capable of shielding non-light-receiving area and manufacturing method
By laying a metal interconnection unit layer in the photodiode to form a shading structure, the problem of non-light-abiding light is solved, the response accuracy and stability of the photodiode are improved, and the control window of the packaging process is improved.
Patent Information
- Application Number
- CN202510326962.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-19
- Publication Date
- 2025-06-17
AI Technical Summary
In existing photodiodes, non-light-receiving devices are affected by light, resulting in a decrease in photoelectric conversion efficiency and insufficient packaging process control window.
By laying a metal interconnection unit layer on the top surface of the photodiode, a shading structure is formed to block the non-light receiving area. The structure includes a multi-layer dielectric and metal layer, and the occlusion structure is precisely designed by photolithography and etching processes.
It effectively prevents unnecessary light from being exposed to light in the non-light-receiving area, improves the response accuracy and stability of the photodiode, and significantly improves the control window of the packaging process.
Smart Images
Figure CN120166795A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of microelectronics technology, and particularly to a photosensitive diode structure capable of shielding non-light-receiving areas and a preparation method thereof. Background Art
[0002] A circuit device that encapsulates a light-emitting diode and a photosensitive chip in the same housing, first converts an input electrical signal into an optical signal, and then converts it into an output electrical signal to transmit the electrical signal is called an optocoupler. The optocoupler can achieve complete electrical isolation between the input / output signals and is widely used for isolation in computer peripheral interfaces, military, and input / output signal transmission in high-reliability systems. The circuit consists of two parts. The input part is a high-speed infrared light-emitting diode (LED), and the output part is a photosensitive chip with a silicon photosensitive diode as the photosensitive part, and an open-collector Schottky transistor is used for output.
[0003] The main devices of the optocoupler are photosensitive diodes and NPN transistors, and the characteristics of these devices are sensitive to light. Among them, the photosensitive diode is used to receive the light-emitting signal, and the NPN transistor is used to amplify the signal to drive the subsequent circuit. The device structure and process conditions will affect the intensity and efficiency of receiving the optical signal. At the same time, the dielectric layers outside the light-receiving area have the property of light transmission, and different lighting conditions have different effects on the current characteristics of the photosensitive diode and the NPN transistor, which will affect the optoelectronic conversion efficiency to varying degrees. At present, the transmission delay time of domestic low-voltage high-speed optocouplers is very sensitive to the pasting position of the internal light-emitting diodes, the packaging process requirements are strict, and the process window is insufficient. Summary of the Invention
[0004] In order to overcome the defects of the above-mentioned prior art, the purpose of the present invention is to provide a photosensitive diode structure capable of shielding non-light-receiving areas and a preparation method thereof, so as to solve the technical problem of how to reduce the influence of light on the devices in the non-light-receiving areas in the photosensitive diode.
[0005] The present invention is realized through the following technical solutions: In the first aspect, the present invention provides a photosensitive diode structure capable of shielding non-light-receiving areas, including a photosensitive diode and a metal interconnection unit layer; the metal interconnection unit layer is disposed on the top surface of the photosensitive diode, a light-receiving area is provided at the center position of the top surface of the photosensitive diode, and non-light-receiving areas are distributed on both sides of the light-receiving area; the metal interconnection unit layer forms a shielding structure corresponding to the non-light-receiving areas for shielding the non-light-receiving areas from light.
[0006] Preferably, the metal interconnection unit layer includes a first silicon dioxide dielectric layer, a first metal dielectric layer, a second silicon dioxide dielectric layer, and a second metal dielectric layer; The first silicon dioxide dielectric layer is disposed on the top surface of the photosensitive diode, and the first metal dielectric layer is disposed on the first silicon dioxide dielectric layer and is connected to the top surface of the photosensitive diode through the first silicon dioxide dielectric layer; the second silicon dioxide dielectric layer is disposed on the first metal dielectric layer and is in contact with the first silicon dioxide dielectric layer; the second metal dielectric layer is disposed on the second silicon dioxide dielectric layer and is connected to the first metal dielectric layer through the second silicon dioxide dielectric layer; the first silicon dioxide dielectric layer, the first metal dielectric layer, the second silicon dioxide dielectric layer, and the second metal dielectric layer form a light-shielding structure corresponding to the non-light-receiving area.
[0007] Further, the first metal dielectric layer includes a first metal dielectric ring and a second metal dielectric ring; the second metal dielectric ring is located at the central position of the first silicon dioxide dielectric layer, and the first metal dielectric ring is located outside the second metal dielectric ring; wherein, the inner side of the second metal dielectric ring corresponds to the light-receiving area, and the outer side of the second metal dielectric ring corresponds to the non-light-receiving area; in the non-light-receiving area, the first metal dielectric ring and the second metal dielectric ring are connected to the top surface of the photosensitive diode through the first silicon dioxide dielectric layer to form a primary shielding structure.
[0008] Furthermore, a plurality of first contact holes are provided on the first silicon dioxide dielectric layer; the first metal dielectric ring and the second metal dielectric ring are respectively connected to the top surface of the photosensitive diode through the plurality of first contact holes, and the diameters of the first metal dielectric ring and the second metal dielectric ring at the first contact holes correspond to the aperture diameters of the first contact holes.
[0009] Furthermore, the second metal dielectric layer includes a first aluminum dielectric ring and a second aluminum dielectric ring; the second aluminum dielectric ring is located at the central position of the second silicon dioxide dielectric layer, and the first aluminum dielectric ring is located outside the second aluminum dielectric ring; wherein, the inner side of the second aluminum dielectric ring corresponds to the light-receiving area, and the outer side of the second aluminum dielectric ring corresponds to the non-light-receiving area; in the non-light-receiving area, the first aluminum dielectric ring and the second aluminum dielectric ring are respectively in contact with the first metal dielectric ring and the second metal dielectric ring through the second silicon dioxide dielectric layer to form a secondary shielding structure.
[0010] Furthermore, a plurality of second contact holes are provided on the second silicon dioxide dielectric layer; the first aluminum dielectric ring and the second aluminum dielectric ring are respectively in contact with the first metal dielectric ring and the second metal dielectric ring through the plurality of second contact holes, and the diameters of the first aluminum dielectric ring and the second aluminum dielectric ring at the second contact holes correspond to the aperture diameters of the second contact holes.
[0011] Furthermore, the positions of the first aluminum dielectric ring and the second aluminum dielectric ring respectively correspond to those of the first metal dielectric ring and the second metal dielectric ring.
[0012] Furthermore, a passivation dielectric layer is covered on the first aluminum dielectric ring and the second aluminum dielectric ring.
[0013] Preferably, the photosensitive diode includes an N-type buried layer, an N-type epitaxial layer, a P-type doped region, and an N-type doped region; The N-type buried layer is located at the bottom, the N-type epitaxial layer is disposed on the N-type buried layer, the P-type doped region is located at the top center position of the N-type epitaxial layer and corresponds to the light-receiving region; the N-type doped region is at the top of the N-type epitaxial layer and is distributed on both sides of the P-type doped region and corresponds to the non-light-receiving region; wherein, both the P-type doped region and the N-type doped region are in contact with the first metal dielectric layer.
[0014] In a second aspect, the present invention also provides a method for manufacturing a photosensitive diode structure capable of shielding the non-light-receiving region, for obtaining a photosensitive diode structure capable of shielding the non-light-receiving region as described above, including the following processes: Divide the light-receiving region and the non-light-receiving region on the top surface of the photosensitive diode; generate a first silicon dioxide dielectric layer on the light-receiving region and the non-light-receiving region, form a plurality of first contact holes in the first silicon dioxide dielectric layer, and contact the first metal dielectric layer with the top surface of the photosensitive diode through the first contact holes, and form a primary shielding structure corresponding to the position of the non-light-receiving region through photolithography and etching processes; Generate a second silicon dioxide dielectric layer on the first silicon dioxide dielectric layer; form a plurality of second contact holes in the second silicon dioxide dielectric layer, contact the second metal dielectric layer with the first metal dielectric layer through the second contact holes, and form a secondary shielding structure corresponding to the position of the non-light-receiving region through photolithography and etching processes; Lay a passivation layer on the second metal dielectric layer, perform photolithography and etching on the passivation layer to form a passivation protection layer; Finally, through a metal annealing process and electrical parameter testing, the manufacturing work of the photosensitive diode structure capable of shielding the non-light-receiving region is completed.
[0015] Compared with the prior art, the present invention has the following beneficial technical effects: The present invention provides a photosensitive diode structure capable of shielding the non-light-receiving region. By forming a shielding structure in the non-light-receiving region through a metal interconnection unit layer, unnecessary light illumination of the non-light-receiving region is effectively prevented. The light-receiving condition of the photosensitive diode is made more single, and only the light-receiving region receives light illumination, thereby improving the response accuracy and stability of the photosensitive diode. The structure of the present invention optimizes the light illumination condition, reduces packaging problems caused by light interference in the non-light-receiving region, and thus significantly improves the control window of the trial packaging process. This means that during the packaging process, the working state of the light-emitting diode can be more accurately controlled, improving the packaging accuracy and stability.
[0016] Furthermore, the metal interconnect unit layer includes a first silicon dioxide dielectric layer, a first metal dielectric layer, a second silicon dioxide dielectric layer, and a second metal dielectric layer. The metal layer and the dielectric layer together block light from entering the non-light-receiving area, which helps reduce unnecessary light interference and improve the performance and stability of the photosensitive diode.
[0017] Furthermore, the second metal dielectric ring is located at the center of the first silicon dioxide dielectric layer, and its inner side corresponds to the light-receiving area, ensuring that only the light-receiving area can receive light. The second metal dielectric ring itself and the first metal dielectric ring on its outer side play a shielding role, effectively controlling the light-receiving range of the photosensitive diode. In the non-light-receiving area, the first metal dielectric ring and the second metal dielectric ring are connected to the top surface of the photosensitive diode through the first silicon dioxide dielectric layer, forming a primary shielding structure that enhances the light-shielding effect, reduces the light interference received by the non-light-receiving area, and thus improves the performance stability and accuracy of the photosensitive diode. The first metal dielectric ring and the second metal dielectric ring not only act as light shields but also serve as part of the circuit for signal transmission, power supply connection, or other electrical functions. By precisely designing the size, shape, and position of the metal rings, the electrical performance of the photosensitive diode can be optimized, such as reducing resistance and improving signal transmission efficiency.
[0018] Furthermore, the first contact hole allows the first metal dielectric ring and the second metal dielectric ring to achieve precise electrical connection with the top surface of the photosensitive diode, ensuring the accurate transmission of signals and power. By precisely controlling the diameter and aperture of the first contact hole and ensuring that the sizes of the first metal dielectric ring and the second metal dielectric ring match these holes, the contact resistance can be minimized. This helps improve the response speed and efficiency of the photosensitive diode and reduces energy loss.
[0019] Furthermore, the second aluminum dielectric ring is located at the center of the second silicon dioxide dielectric layer, with its inner side corresponding to the light-receiving area and its outer side corresponding to the non-light-receiving area. This not only ensures that the light-receiving area can receive light but also forms an effective secondary shielding structure in the non-light-receiving area through the second aluminum dielectric ring and the first aluminum dielectric ring, reducing the light interference received by the non-light-receiving area. The second metal dielectric layer is in contact with the first metal dielectric layer through the second silicon dioxide dielectric layer, forming a stable interlayer connection, which helps enhance the overall stability of the photosensitive diode structure and prevent connection failure or damage caused by mechanical stress during packaging, testing, and use.
[0020] The present invention also provides a method for fabricating a photosensitive diode structure capable of shielding a non-light-receiving area. On the top surface of the photosensitive diode, a light-receiving area and a non-light-receiving area are divided according to design requirements. The light-receiving area is the area where the photosensitive diode receives light signals, while the non-light-receiving area should avoid interference from light signals. A first silicon dioxide dielectric layer is formed on the entire top surface of the photosensitive diode. A number of first contact holes are formed in the first silicon dioxide dielectric layer, and the positions of these contact holes correspond to the points that need to contact the top surface of the photosensitive diode. Through the first contact holes, the first metal dielectric layer is brought into contact with the top surface of the photosensitive diode to form an electrical connection. Using photolithography and etching processes, a first-level shielding structure is formed at the position corresponding to the non-light-receiving area on the first silicon dioxide dielectric layer to shield the non-light-receiving area and prevent light signal interference. A second silicon dioxide dielectric layer is formed on the first silicon dioxide dielectric layer. A number of second contact holes are formed in the second silicon dioxide dielectric layer. Through the second contact holes, the second metal dielectric layer is brought into contact with the first metal dielectric layer. Using photolithography and etching processes, a second-level shielding structure is formed at the position corresponding to the non-light-receiving area on the second silicon dioxide dielectric layer to enhance the shielding effect on the non-light-receiving area. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 FIG. is a schematic cross-sectional structure diagram of the light-receiving area and the non-light-receiving area after the first-layer metal is etched and alloyed in the embodiment of the present invention; Figure 2 FIG. is a schematic cross-sectional structure diagram of the circuit after the inter-metal silicon dioxide dielectric and through holes are etched in the embodiment of the present invention; Figure 3 FIG. is a schematic cross-sectional structure diagram of the circuit after the second-layer metal is etched in the embodiment of the present invention; Figure 4 FIG. is a schematic cross-sectional structure diagram of the circuit after the composite film passivation layer is deposited and etched in the embodiment of the present invention; In the figure: 1. Photosensitive diode; 2. First silicon dioxide dielectric layer; 3. First metal dielectric; 4. Second metal dielectric; 5. Light-receiving area; 6. Non-light-receiving area; 7. Second silicon dioxide dielectric layer; 8. First aluminum dielectric; 9. Second aluminum dielectric; 10. Passivation dielectric layer; 11. N-type buried layer; 12. N-type epitaxial layer; 13. P-type doped region; 14. N-type doped region; 21. First contact hole; 71. Second contact hole. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0022] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.
[0023] The object of the present invention is to provide a photosensitive diode structure capable of shielding the non-light-receiving area and a preparation method thereof, so as to solve the technical problem of how to reduce the influence of light on the devices in the non-light-receiving area in a photosensitive diode.
[0024] The present invention will be further described in detail below with reference to the accompanying drawings: Embodiment 1 See Figure 1 , in an embodiment of the present invention, a photosensitive diode structure capable of shielding the non-light-receiving area is provided, including a photosensitive diode 1 and a metal interconnection unit layer; the metal interconnection unit layer is disposed on the top surface of the photosensitive diode 1, a light-receiving area 5 is provided at the center position of the top surface of the photosensitive diode 1, and non-light-receiving areas 6 are distributed on both sides of the light-receiving area 5; the metal interconnection unit layer forms a shielding structure corresponding to the non-light-receiving area 6 for shielding the non-light-receiving area 6 from light.
[0025] Specifically, the metal interconnection unit layer includes a first silicon dioxide dielectric layer 2, a first metal dielectric layer; a second silicon dioxide dielectric layer 7 and a second metal dielectric layer; the first silicon dioxide dielectric layer 2 is disposed on the top surface of the photosensitive diode 1, the first metal dielectric layer is disposed on the first silicon dioxide dielectric layer 2 and is connected to the top surface of the photosensitive diode 1 through the first silicon dioxide dielectric layer 2; the second silicon dioxide dielectric layer 7 is disposed on the first metal dielectric layer and is in contact with the first silicon dioxide dielectric layer 2; the second metal dielectric layer is disposed on the second silicon dioxide dielectric layer 7 and is connected to the first metal dielectric layer through the second silicon dioxide dielectric layer 7; the first silicon dioxide dielectric layer 2, the first metal dielectric layer; the second silicon dioxide dielectric layer 7 and the second metal dielectric layer form a light-shielding structure corresponding to the non-light-receiving area 6.
[0026] Among them, the first metal dielectric layer includes a first metal dielectric ring 3 and a second metal dielectric ring 4; the second metal dielectric ring 4 is located at the center position of the first silicon dioxide dielectric layer 2, and the first metal dielectric ring 3 is located outside the second metal dielectric ring 4; wherein, the inner side of the second metal dielectric ring 4 corresponds to the light-receiving area 5, and the outer side of the second metal dielectric ring 4 corresponds to the non-light-receiving area 6; in the non-light-receiving area 6, the first metal dielectric ring 3 and the second metal dielectric ring 4 are connected to the top surface of the photosensitive diode 1 through the first silicon dioxide dielectric layer 2 to form a primary shielding structure.
[0027] Specifically, a plurality of first contact holes 21 are provided on the first silicon dioxide dielectric layer 2; the first metal dielectric ring 3 and the second metal dielectric ring 4 are respectively connected to the top surface of the photosensitive diode 1 through a plurality of first contact holes 21, and the diameters of the first metal dielectric ring 3 and the second metal dielectric ring 4 at the first contact holes 21 correspond to the apertures of the first contact holes 21.
[0028] Specifically, the second metal dielectric layer includes a first aluminum dielectric ring 8 and a second aluminum dielectric ring 9; the second aluminum dielectric ring 9 is located at the center of the second silicon dioxide dielectric layer 7, and the first aluminum dielectric ring 8 is located outside the second aluminum dielectric ring 9; wherein, the inner side of the second aluminum dielectric ring 9 corresponds to the light-receiving area 5, and the outer side of the second aluminum dielectric ring 9 corresponds to the non-light-receiving area 6; within the non-light-receiving area 6, the first aluminum dielectric ring 8 and the second aluminum dielectric ring 9 are respectively in contact with the first metal dielectric ring 3 and the second metal dielectric ring 4 through the second silicon dioxide dielectric layer 7, forming a secondary shielding structure.
[0029] Wherein, a plurality of second contact holes 71 are provided on the second silicon dioxide dielectric layer 7; the first aluminum dielectric ring 8 and the second aluminum dielectric ring 9 are respectively in contact with the first metal dielectric ring 3 and the second metal dielectric ring 4 through the plurality of second contact holes 7, and the diameters of the first aluminum dielectric ring 8 and the second aluminum dielectric ring 9 at the second contact holes 71 correspond to the aperture diameters of the second contact holes 71.
[0030] Wherein, the positions of the first aluminum dielectric ring 8 and the second aluminum dielectric ring 9 respectively correspond to the positions of the first metal dielectric ring 3 and the second metal dielectric ring 4.
[0031] Wherein, a passivation dielectric layer 10 is covered on the first aluminum dielectric ring 8 and the second aluminum dielectric ring 9.
[0032] Wherein, the passivation dielectric layer 10 is obtained by the combination of silicon dioxide and silicon oxide.
[0033] Specifically, the photosensitive diode 1 includes an N-type buried layer 11, an N-type epitaxial layer 12, a P-type doping region 13, and an N-type doping region 14; The N-type buried layer 11 is located at the bottom, the N-type epitaxial layer 12 is disposed on the N-type buried layer 11, the P-type doping region 13 is located at the top center position of the N-type epitaxial layer 12 and corresponds to the position of the light-receiving area 5; the N-type doping region 14 is at the top of the N-type epitaxial layer 12 and is distributed on both sides of the P-type doping region 13 and corresponds to the position of the non-light-receiving area 6; wherein, both the P-type doping region 13 and the N-type doping region 14 are in contact with the first metal dielectric layer.
[0034] In the optocoupler product of this embodiment, the photosensitive diode is made of a CB junction diode composed of an epitaxial layer and a base region, and a pure aluminum Schottky process with single-layer metal interconnection is adopted. Light can affect the illumination conditions of the light-receiving area through the dielectric layer at different angles, and can also affect the current characteristics of devices other than the non-light-receiving area through the dielectric layer. Therefore, a second-layer metal light-shielding graphic structure is added to make the light-receiving variables of the photosensitive chip single.
[0035] This embodiment is based on the original single-layer metal process. By adding an interlayer dielectric deposition process, a dielectric planarization process, a via process, and a metal sputtering process, a second metal layer structure is added to serve as a light-shielding layer for the non-light-receiving area and related metal interconnections, realizing the light shielding of the non-light-receiving area and making the light variables in the light-receiving area single.
[0036] Embodiment 2 The present invention provides a manufacturing method for a photosensitive diode structure capable of shielding a non-light-receiving area, used to obtain a photosensitive diode structure capable of shielding a non-light-receiving area as described above, including the following processes: Step 1, divide the light-receiving area 5 and the non-light-receiving area 6 on the top surface of the photosensitive diode 1; generate a first silicon dioxide dielectric layer 2 on the light-receiving area 5 and the non-light-receiving area 6, form a number of first contact holes 21 in the first silicon dioxide dielectric layer 2, contact the first metal dielectric layer with the top surface of the photosensitive diode 1 through the first contact holes 21, and form a primary shielding structure at the position corresponding to the non-light-receiving area 6 through photolithography and etching processes.
[0037] Among them, through a mature optocoupler process, an active region device structure is formed, and then a first silicon dioxide dielectric layer 2 with a thickness of 175 Å is grown by the LPCVD process. A silicon dioxide thin film with a thickness of 7500 Å is deposited by the APCVD process, and then a densification process is performed to form a dielectric layer between the metal and the device and an antireflection thin film in the light-receiving area. Then, through processes such as photolithography, etching, and thin film of the first contact holes 21 and the first metal dielectric layer, a basic circuit structure, metal interconnections, and photosensitive diode structure as shown in Figure 1 are formed.
[0038] Step 2, generate a second silicon dioxide dielectric layer 7 on the first silicon dioxide dielectric layer 2; form a number of second contact holes 71 in the second silicon dioxide dielectric layer 7, contact the second metal dielectric layer with the first metal dielectric layer through the second contact holes 71, and form a secondary shielding structure at the position corresponding to the non-light-receiving area 6 through photolithography and etching processes.
[0039] Among them, a second silicon dioxide dielectric layer 7 with a thickness of 5000 Å and 5800 Å is deposited by the PECVD and SOG spin coating processes respectively, the dielectric planarization is realized through the SOG back etching process, and finally a second silicon dioxide dielectric layer 7 with a thickness of 8000 Å is deposited by the PECVD to form the final interlayer dielectric. Then, a circuit cross-sectional structure containing inter-metal silicon dioxide dielectric and vias as shown in Figure 2 is formed through processes such as via layer photolithography and etching.
[0040] Among them, an aluminum-silicon-copper alloy thin film with a thickness of 15000 Å is deposited by the metal sputtering process, and a structure as shown in Figure 3As shown, a circuit structure having a second metal dielectric layer connection, a light-receiving region, and a non-light-receiving region pattern.
[0041] Step 3, a passivation layer 10 is laid on the second metal dielectric layer, and photolithography and etching are performed on the passivation layer 10 to form a passivation protection layer; Among them, a silicon dioxide thin film with a thickness of 5000 Å and a silicon nitride thin film with a thickness of 3000 Å are respectively deposited by APCVD to form a passivation layer, and processes such as photolithography and etching are performed on the passivation layer to form a passivation protection layer with a bonding contact pattern as shown in Figure 4 As shown; Step 4, finally, through a metal annealing process and electrical parameter testing, the production of a photosensitive diode structure capable of blocking the non-light-receiving region is completed.
[0042] In summary, the present invention also provides a method for manufacturing a photosensitive diode structure capable of blocking the non-light-receiving region. On the top surface of the photosensitive diode, the light-receiving region and the non-light-receiving region are divided according to design requirements. The light-receiving region is the region where the photosensitive diode receives light signals, while the non-light-receiving region should avoid interference from light signals. A first silicon dioxide dielectric layer is formed on the entire top surface of the photosensitive diode. A number of first contact holes are formed in the first silicon dioxide dielectric layer, and the positions of these contact holes correspond to the points that need to be in contact with the top surface of the photosensitive diode. Through the first contact holes, the first metal dielectric layer is brought into contact with the top surface of the photosensitive diode to form an electrical connection. Using photolithography and etching processes, a first-level shielding structure is formed at the position corresponding to the non-light-receiving region on the first silicon dioxide dielectric layer to shield the non-light-receiving region and prevent light signal interference. A second silicon dioxide dielectric layer is formed on the first silicon dioxide dielectric layer. A number of second contact holes are formed in the second silicon dioxide dielectric layer. Through the second contact holes, the second metal dielectric layer is brought into contact with the first metal dielectric layer. Using photolithography and etching processes, a second-level shielding structure is formed at the position corresponding to the non-light-receiving region on the second silicon dioxide dielectric layer to enhance the shielding effect on the non-light-receiving region.
[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: it is still possible to modify the specific implementation manners of the present invention or make equivalent replacements, and any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.
Claims
1. A photodiode structure capable of shielding a non-light-receiving area, characterized in that: The invention comprises a photosensitive diode (1) and a metal interconnection unit layer; the metal interconnection unit layer is arranged on the top surface of the photosensitive diode (1); a light receiving area (5) is provided at the center of the top surface of the photosensitive diode (1), and non-light receiving areas (6) are distributed on both sides of the light receiving area (5); the metal interconnection unit layer forms a shielding structure corresponding to the non-light receiving area (6) for shielding the non-light receiving area (6) from light.
2. A photodiode structure capable of shielding a non-light-receiving area according to claim 1, characterized in that: The metal interconnect unit layer comprises a first silicon dioxide dielectric layer (2), a first metal dielectric layer; a second silicon dioxide dielectric layer (7) and a second metal dielectric layer; The first silicon dioxide dielectric layer (2) is arranged on the top surface of the photosensitive diode (1); the first metal dielectric layer is arranged on the first silicon dioxide dielectric layer (2) and is connected to the top surface of the photosensitive diode (1) through the first silicon dioxide dielectric layer (2); the second silicon dioxide dielectric layer (7) is arranged on the first metal dielectric layer and is in contact with the first silicon dioxide dielectric layer (2); the second metal dielectric layer is arranged on the second silicon dioxide dielectric layer (7) and is connected to the first metal dielectric layer through the second silicon dioxide dielectric layer (7); the first silicon dioxide dielectric layer (2), the first metal dielectric layer; the second silicon dioxide dielectric layer (7) and the second metal dielectric layer form a light shielding structure corresponding to the non-light receiving area (6).
3. A photodiode structure capable of shielding a non-light receiving area according to claim 2, characterized in that: The first metal dielectric layer comprises a first metal dielectric ring (3) and a second metal dielectric ring (4); the second metal dielectric ring (4) is located at the center of the first silicon dioxide dielectric layer (2), and the first metal dielectric ring (3) is located outside the second metal dielectric ring (4); wherein the inside of the second metal dielectric ring (4) corresponds to a light receiving area (5), and the outside of the second metal dielectric ring (4) corresponds to a non-light receiving area (6); within the non-light receiving area (6), the first metal dielectric ring (3) and the second metal dielectric ring (4) are connected to the top surface of the photosensitive diode (1) through the first silicon dioxide dielectric layer (2) to form a primary shielding structure.
4. A photodiode structure capable of shielding a non-light receiving area according to claim 3, characterized in that: A plurality of first contact holes (21) are provided on the first silicon dioxide dielectric layer (2); the first metal dielectric ring (3) and the second metal dielectric ring (4) are respectively connected to the top surface of the photosensitive diode (1) through the plurality of first contact holes (21), and the diameters of the first metal dielectric ring (3) and the second metal dielectric ring (4) in the first contact holes (21) correspond to the aperture of the first contact holes (21).
5. The photodiode structure capable of shielding a non-light receiving area according to claim 3, characterized in that: The second metal dielectric layer comprises a first aluminum dielectric ring (8) and a second aluminum dielectric ring (9); the second aluminum dielectric ring (9) is located at the center of the second silicon dioxide dielectric layer (7), and the first aluminum dielectric ring (8) is located outside the second aluminum dielectric ring (9); wherein the inside of the second aluminum dielectric ring (9) corresponds to the light receiving area (5), and the outside of the second aluminum dielectric ring (9) corresponds to the non-light receiving area (6); within the non-light receiving area (6), the first aluminum dielectric ring (8) and the second aluminum dielectric ring (9) are in contact with the first metal dielectric ring (3) and the second metal dielectric ring (4) respectively through the second silicon dioxide dielectric layer (7), thereby forming a secondary shielding structure.
6. A photodiode structure capable of shielding a non-light receiving area according to claim 5, characterized in that: A plurality of second contact holes (71) are provided on the second silicon dioxide dielectric layer (7); the first aluminum dielectric ring (8) and the second aluminum dielectric ring (9) are in contact with the first metal dielectric ring (3) and the second metal dielectric ring (4) respectively through the plurality of second contact holes (7); and the diameters of the first aluminum dielectric ring (8) and the second aluminum dielectric ring (9) in the second contact holes (71) correspond to the apertures of the second contact holes (71).
7. A photodiode structure capable of shielding a non-light receiving area according to claim 6, characterized in that: The positions of the first aluminum dielectric ring (8) and the second aluminum dielectric ring (9) correspond to the positions of the first metal dielectric ring (3) and the second metal dielectric ring (4), respectively.
8. The photodiode structure capable of shielding a non-light-receiving area according to claim 6, characterized in that: A passivation dielectric layer (10) is provided on the first aluminum dielectric ring (8) and the second aluminum dielectric ring (9).
9. The photodiode structure capable of shielding a non-light-receiving area according to claim 1, characterized in that: The photosensitive diode (1) comprises an N-type buried layer (11), an N-type epitaxial layer (12), a P-type doped region (13), and an N-type doped region (14); The N-type buried layer (11) is located at the bottom, the N-type epitaxial layer (12) is arranged on the N-type buried layer (11), the P-type doped region (13) is located at the top center of the N-type epitaxial layer (12), and corresponds to the position of the light receiving region (5); the N-type doped region (14) is at the top of the N-type epitaxial layer (12) and is distributed on both sides of the P-type doped region (13), and corresponds to the position of the non-light receiving region (6); wherein both the P-type doped region (13) and the N-type doped region (14) are in contact with the first metal dielectric layer.
10. A method for manufacturing a photodiode structure capable of shielding a non-light-receiving area, for obtaining a photodiode structure capable of shielding a non-light-receiving area as claimed in any one of claims 1 to 9, characterized in that: The process includes the following: The top surface of the photosensitive diode (1) is divided into a light receiving area (5) and a non-light receiving area (6); a first silicon dioxide dielectric layer (2) is formed on the light receiving area (5) and the non-light receiving area (6), a plurality of first contact holes (21) are formed in the first silicon dioxide dielectric layer (2), a first metal dielectric layer is contacted with the top surface of the photosensitive diode (1) through the first contact holes (21), and a primary shielding structure is formed at a position corresponding to the non-light receiving area (6) through a photolithography and etching process; A second silicon dioxide dielectric layer (7) is formed on the first silicon dioxide dielectric layer (2); a plurality of second contact holes (71) are formed on the second silicon dioxide dielectric layer (7), the second metal dielectric layer is brought into contact with the first metal dielectric layer through the second contact holes (71), and a secondary shielding structure is formed at a position corresponding to the non-light-receiving area (6) through photolithography and etching processes; A passivation layer (10) is laid on the second metal dielectric layer, and the passivation layer (10) is photoetched and etched to form a passivation protection layer; Finally, after metal annealing process and electrical parameter testing, the production of the photodiode structure that can shield the non-light-receiving area is completed.